Funding for a period of one year is requested to investigate the hormonal and social variables effecting sexual behavior in stumptail macaques (Macaca acrtoides). The specific aims of this project are to determine the relative roles of female gonadal hormones and female dominance status in the expression of sexual behavior among the members of a stable social group living in a large outdoor compound. Quantitative obeservations will be made of the sexual behavior and dominance relationships of a group of 18 monkeys which includes two adult males and 10 adult females. The menstrual cycle of the females will be monitored by vaginal swabbing. The relationships among copulatory behavior, phase of the female's menstrual cycle and female social status will be assessed. It is suggested that, unlike copulation in laboratory test situations copulation among members of a social group may be more dependent upon female gonadal hormone status and less dependent upon female social status. These data will be important in furthering our knowledge of the mechanisms regulating sexual behavior in primates and in facilitating the construction of general theories of sexual behavior which apply to all primates including humans.